Typical solenoid valve systems utilize a binary-type fluid power positioning system in which the solenoid valve is directed to one of two or three positions. In many existing two-position valves, the solenoid is coupled to an actuator assembly with a double-acting piston. When the solenoid valve is in the first position, air (or other fluid) is directed to one side of the piston, while air on the second (opposite) side of the piston is vented to atmosphere. When the solenoid valve is in the second position, air is directed to the second side of the piston, and air on the first side of the piston is vented to atmosphere. In such examples, essentially the entire volume of air on one side of the piston is vented to atmosphere with each piston stroke. Such designs therefore require comparatively high volumes of air to actuate the piston.
Typical three-position solenoid valve systems operate in a fashion similar to the two-position systems described above. However, in certain examples the solenoid valve can be placed in a third position that effectively shuts off air to the actuator. As in the case of the two-position valve described above, essentially the entire volume of air on one side of the piston is vented to atmosphere with each piston stroke.
It is therefore desirable to provide a solenoid valve and actuator system that captures a portion of the air that is typically vented to atmosphere during movement of the actuator. The air that is captured can be directed to the opposing side of the actuator, thereby reducing the volume of air required to redirect the actuator. It is also desirable to provide such a solenoid valve that can be retrofitted to replace existing solenoid valve systems without extensive modifications.